Scan method, scan system and radiation scan controller

ABSTRACT

This invention provides a scan method, scan system and radiation scan controller, and relates to the field of radiation. Wherein, the scan method of this invention comprises: obtaining detection data of an object to be inspected under radiation scanning using a detector; adjusting an accelerator output beam dose rate and/or an output electron beam energy level of a radiation emission device according to the detection data. With this method, working conditions of the accelerator of the radiation emission device may be adjusted according to the detection data detected by the detector, so that for a region having a larger mass thickness, a higher output beam dose rate or a higher electron beam output energy level is adopted to guarantee satisfied imaging technical indexes, for a region having a smaller mass thickness, a lower output beam dose rate or a lower electron beam output energy level is adopted to reduce the environmental dose level while guaranteeing satisfied imaging technical indexes.

FIELD OF THE INVENTION

This invention relates to the field of radiation, particularly to a scanmethod, scan system and controller.

BACKGROUND ART

Currently, most of the X-ray light sources used in real-timecontainers/vehicle scanning and imaging systems are produced by linearelectron accelerators having constant output dose rates. In general,imaging technical indexes of an inspection system, especially systempenetrability, depends on the output dose rate of its accelerator, i.e.,the higher the dose rate is, the better the penetrability is. However,since X-ray may cause radiation damage to human bodies and theenvironment, it is necessary to control the accelerator output dose ratein operation, or provide additional shielding protection or othermeasures, to meet the requirement of the environmental dose level.

In order to meet the requirements for scanning under various differentconditions, the accelerators' dose rates and energy levels of imagingsystems are usually set to their maximum penetration and materialresolution setting values that are allowed by the systems. However, inactual situation, the cargoes under inspection or the amounts of cargoescarried by containers/vehicles are usually different, so, therequirements of X-ray output dose rates and energy levels for aparticular scan imaging system may vary greatly, which may cause a doserate above an actually required value in scanning, additional shieldingprotection cost, or unnecessary radiation to relevant operators. If asuitable accelerator dose rate or electron beam energy level may beselected according to actual situations of cargoes to be inspected, animaging inspection system that may guarantee satisfied system imagingtechnical indexes and image quality without causing unnecessary cost forradiation shielding protection may be realized, which has importantpractical significance.

There is a technique in the prior art for imaging different regions ofan object to be inspected using a multi-dose and multi-energyaccelerator, which mainly relates to a fast inspection system, forexample, a head region of a vehicle where the driver locates may bescanned at a lower safety dose rate which may not cause damage to thedriver, and a cargo region of the vehicle may be scanned at a higherdose rate. This scheme has gained successful applications in X-ray fastinspection system devices, however, it cannot be adjusted according tovaried situations of cargoes, and thus has certain limitation.

SUMMARY OF INVENTION

An object of this invention is to provide a solution capable of takingboth the requirement of imaging technical indexes of as system and therequirement of the environmental dose level into consideration.

According to an aspect of this invention, a scan method is provided,comprising: acquiring detection data of an object to be inspected underradiation scanning using a detector; adjusting an accelerator outputbeam dose rate and/or an output electron beam energy level of aradiation emission device according to the detection data.

Optionally, the detection data comprises a sampling value of thedetector and/or transparency information of the object to be inspected;adjusting an accelerator output beam dose rate and/or an output electronbeam energy level of a radiation emission device according to thedetection data comprises: adjusting an accelerator output beam dose rateand/or an output electron beam energy level of a radiation emissiondevice according to the sampling value and/or transparency informationof the object to be inspected.

Optionally, adjusting an accelerator output beam dose rate and/or anoutput electron beam energy level of a radiation emission deviceaccording to the detection data comprises: during a movement of theobject to be inspected relative to the radiation emission device and thedetector, adjusting an accelerator output beam dose rate and/or anoutput electron beam energy level of a radiation emission deviceaccording to real-time detection data obtained by the detector from ascanning region of the object to be inspected.

Optionally, adjusting an accelerator output beam dose rate and/or anoutput electron beam energy level of a radiation emission deviceaccording to the detection data comprises: acquiring overall scanningdata of the object to be inspected using the detector; analyzing theoverall scanning data to determine a main scanning region of the objectto be inspected, wherein the main scanning region comprises a lowpenetration region or a region suspected to be a contraband item;determine an accelerator output beam dose rate and/or an output electronbeam energy level according to detection data of the main scanningregion, to scan the main scanning region.

Optionally, the detection data is a sampling value of a detectionregion; adjusting an output electron beam energy level of a radiationemission device according to the detection data comprises: comparing thesampling value with a predetermined sampling threshold value; if thesampling value is below a predetermined lower sampling threshold value,increasing the accelerator output beam dose rate and/or the outputelectron beam energy level; if the sampling value is above apredetermined upper sampling threshold value, decreasing the acceleratoroutput beam dose rate and/or the output electron beam energy level.

Optionally, acquiring detection data of an object to be inspected underradiation scanning through a detector comprises: dividing data acquiredby the detector into sections according to a predetermined detectiongranularity; using an average value of data items from the same sectionas the sampling value; or extracting a minimum value of data items fromthe same section as the sampling value.

Optionally, the detection data is transparency information of the objectto be inspected; adjusting an accelerator output beam dose rate and/oran output electron beam energy level of a radiation emission deviceaccording to the detection data comprises: comparing the transparencyinformation with a predetermined transparency threshold value; if thetransparency information is below a predetermined lower transparencythreshold value, increasing the accelerator output beam dose rate and/orthe output electron beam energy level; if the transparency informationis above a predetermined upper transparency threshold value, decreasingthe accelerator output beam dose rate and/or the output electron beamenergy level.

Optionally, acquiring detection data of an object to be inspected underradiation scanning through a detector comprises: acquiring initialtransparency information according to the detection data; correcting theinitial transparency information according to a background image and anair image to obtain the transparency information.

Optionally, adjusting an accelerator output beam dose rate and/or anoutput electron beam energy level of a radiation emission deviceaccording to the detection data comprises: determining an ideal outputbeam dose rate and/or an ideal output electron beam energy levelaccording to a conversion policy for converting the detection data tothe ideal accelerator output beam dose rate and/or the ideal outputelectron beam energy level; adjusting the accelerator output beam doserate and/or the output electron beam energy level to the ideal outputbeam dose rate and/or the ideal output electron beam energy level.

Optionally, the accelerator of the radiation emission device comprisesmultiple output beam dose rate levels and/or multiple output electronbeam energy levels, each level having a fixed output beam dose rateand/or a fixed output electron beam energy value; adjusting anaccelerator output beam dose rate and/or an output electron beam energylevel of a radiation emission device according to the detection datacomprises: adjusting the accelerator output beam dose rate and/or theoutput electron beam energy level of the radiation emission device to acertain level according to the detection data.

With this method, working conditions of the accelerator of the radiationemission device may be adjusted according to the detection data detectedby the detector, so that for a region having a larger mass thickness, ahigher output beam dose rate or a higher electron beam output energylevel is adopted to guarantee satisfied imaging technical indexes, for aregion having a smaller mass thickness, a lower output beam dose rate ora lower electron beam output energy level is adopted to reduce theenvironmental dose level while guaranteeing satisfied imaging technicalindexes.

According to another aspect of this invention, a radiation scancontroller is provided, comprising: a data acquisition module foracquiring detection data of an object to be inspected under radiationscanning using a detector; an adjustment module for adjusting anaccelerator output beam dose rate and/or an output electron beam energylevel of a radiation emission device according to the detection data.

Optionally, the detection data comprises a sampling value of thedetector and/or transparency information of the object to be inspected;the adjustment module is further used to adjust an accelerator outputbeam dose rate and/or an output electron beam energy level of aradiation emission device according to the sampling value and/ortransparency information of the object to be inspected.

Optionally, the adjustment module is further used to: during a movementof the object to be inspected relative to the radiation emission deviceand the detector, adjust the accelerator output beam dose rate and/orthe output electron beam energy level of the radiation emission deviceaccording to real-time detection data obtained by the detector from ascanning region of the object to be inspected.

Optionally, the adjustment module is further used to: acquire overallscanning data of the object to be inspected; analyze the overallscanning data to determine a main scanning region of the object to beinspected, wherein the main scanning region comprises a low penetrationregion or a region suspected to be a contraband item; determine anaccelerator output beam dose rate and/or an output electron beam energylevel according to detection data of the main scanning region, to scanthe main scanning region.

Optionally, the detection data is a sampling value of a detectionregion; the adjustment module comprises: a comparison unit for comparingthe sampling value with a predetermined sampling threshold value; anemission adjustment unit for, if the sampling value is below apredetermined lower sampling threshold value, increasing the acceleratoroutput beam dose rate and/or the output electron beam energy level; ifthe sampling value is above a predetermined upper sampling thresholdvalue, decreasing the accelerator output beam dose rate and/or theoutput electron beam energy level.

Optionally, the data acquisition module is further used to: divide dataacquired by the detector into sections according to a predetermineddetection granularity; use an average value of data items from the samesection as the sampling value; or extract a minimum value of data itemsfrom the same section as the sampling value.

Optionally, the detection data is transparency information of the objectto be inspected; the adjustment module further comprises: a comparisonunit for comparing the transparency information with a predeterminedtransparency threshold value; an emission adjustment unit for, if thetransparency information is below a predetermined lower transparencythreshold value, increasing the accelerator output beam dose rate and/orthe output electron beam energy level; if the transparency informationis above a predetermined upper transparency threshold value, decreasingthe accelerator output beam dose rate and/or the output electron beamenergy level.

Optionally, the data acquisition module is further used to: acquireinitial transparency information according to the detection data;correct the initial transparency information according to a backgroundimage and an air image to obtain the transparency information.

Optionally, the adjustment module further comprises: an ideal valuedetermination unit for determining an ideal output beam dose rate and/oran ideal output electron beam energy level according to a conversionpolicy for converting the detection data to the ideal accelerator outputbeam dose rate and/or the ideal output electron beam energy level; anemission adjustment unit for adjusting the accelerator output beam doserate and/or the output electron beam energy level to the ideal outputbeam dose rate and/or the ideal output electron beam energy level.

Optionally, the accelerator of the radiation emission device comprisesmultiple output beam dose rate levels and/or multiple output electronbeam energy levels, each level having a fixed output beam dose rateand/or a fixed output electron beam energy value; the adjustment moduleis further used to adjust the accelerator output beam dose rate and/orthe output electron beam energy level of the radiation emission deviceto a certain level according to the detection data.

This controller may adjust working conditions of the accelerator of theradiation emission device according to the detection data detected bythe detector, so that for a region having a larger mass thickness, ahigher output beam dose rate or a higher electron beam output energylevel is adopted to guarantee satisfied imaging technical indexes, for aregion having a smaller mass thickness, a lower output beam dose rate ora lower electron beam output energy level is adopted to reduce theenvironmental dose level while guaranteeing satisfied imaging technicalindexes.

According to still another aspect of this invention, a scan system isprovided, comprising: any controller, detector and radiation emittermentioned above; wherein the detector is used to send detection data tothe controller; the controller is used to send control information tothe radiation emitter for adjusting an accelerator output beam dose rateand/or an output electron beam energy level of the radiation emissiondevice according to the detection data; the radiation emitter is used toemit radiation, adjust the accelerator output beam dose rate and/or theoutput electron beam energy level of the radiation emission deviceaccording to the control information.

This scan system may adjust working conditions of the accelerator of theradiation emission device according to the detection data detected bythe detector, so that for a region having a larger mass thickness, ahigher output beam dose rate or a higher electron beam output energylevel is adopted to guarantee satisfied imaging technical indexes, for aregion having a smaller mass thickness, a lower output beam dose rate ora lower electron beam output energy level is adopted to reduce theenvironmental dose level while guaranteeing satisfied imaging technicalindexes.

DESCRIPTION OF THE DRAWINGS

The accompanying drawings, which are included to provide a furtherunderstanding of the invention and are incorporated in and constitute apart of this specification, illustrate embodiments of the invention, andtogether with the description serve to explain the principles of theinvention, but are not limitation thereof. In the drawings:

FIG. 1 is a schematic view showing the principle of the scan method ofthis invention.

FIG. 2 is a flow chart of an embodiment of the scan method of thisinvention.

FIG. 3 is a flow chart of another embodiment of the scan method of thisinvention.

FIG. 4 is a flow chart of another embodiment of the scan method of thisinvention.

FIG. 5 is a flow chart of another embodiment of the scan method of thisinvention.

FIG. 6 is a schematic view of determining a sampling value in the scanmethod of this invention.

FIG. 7 is a flow chart of another embodiment of the scan method of thisinvention.

FIG. 8 is a schematic view of transparency determination in the scanmethod of this invention.

FIG. 9 is a schematic view of level determination in the scan method ofthis invention.

FIG. 10 is a schematic view of an embodiment of the radiation scancontroller of this invention.

FIG. 11 is a schematic view of another embodiment of the radiation scancontroller of this invention.

FIG. 12 is a schematic view of an embodiment of a scan system of thisinvention.

FIG. 13 is a schematic view of another embodiment of the scan system ofthis invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

Below, the technical solution of this invention will be furtherdescribed in detail with reference to the accompanying drawings andembodiments.

In a process of radiation detection, different data may be obtained by adetector from different regions of an object to be inspected due to itsinterior inhomogeneity. As shown in FIG. 1, an object to be inspectedwhich is a vehicle is shown in the upper portion of FIG. 1, anddetection data of corresponding locations is shown in the lower portion.It can be seen from FIG. 1, low energy radiation is obtained by thedetector from locations on the vehicle having large mass thicknesses;from locations on the vehicle having smaller mass thicknesses or emptyregions, high energy radiation is obtained by the detector. Based on theabove reasons, a higher accelerator output beam dose rate or a higherelectron output beam energy level may be adopted for locations havinglarger mass thicknesses, and a lower accelerator output beam dose rateor a lower electron output beam energy level may be adopted forlocations having smaller mass thicknesses.

FIG. 2 is a flow chart of an embodiment of the scan method of thisinvention.

At step 201, detection data of an object to be inspected under radiationscanning is obtained using a detector.

At step 202, working conditions of a radiation emitter are adjustedaccording to the detection data acquired by the detector. Workingconditions of the radiation emitter comprise an accelerator output beamdose rate and an electron beam energy level. The accelerator output beamdose rate, or the output electron beam energy level, or both of them maybe adjusted.

With this method, working conditions of the accelerator of the radiationemission device may be adjusted according to the detection data detectedby the detector, so that for a region having a larger mass thickness, ahigher output beam dose rate or a higher electron beam output energylevel is adopted to guarantee satisfied imaging technical indexes, for aregion having a smaller mass thickness, a lower output beam dose rate ora lower electron beam output energy level is adopted to reduce theenvironmental dose level while guaranteeing satisfied imaging technicalindexes.

In an embodiment, the detection data may be a sampling value of thedetector, working conditions of the radiation emitter are adjustedaccording to the sampling value; or the detection data may betransparency information of the object to be inspected obtained by thedetector, and working conditions of the radiation emitter are adjustedaccording to the transparency information. In this manner, workingconditions of a radiation emitter may be determined according to asampling value obtained by the detector or transparency information of adetection image. This may facilitate data acquiring and processing, sothat the response speed of the system may be increased.

In an embodiment, if the radiation emitter is a dual-energy device,real-time material discrimination may be performed based on thedetection data to obtain atomic numbers and mass thickness values, andworking conditions of the radiation emitter may be adjusted based onthese informations.

FIG. 3 is a flow chart of another embodiment of the scan method of thisinvention.

At step 301, an object to be inspected moves relative to a detector anda radiation emission device. The object to be inspected gradually passesthrough an electron beam projection region of the radiation emissiondevice.

At step 302, the detector obtains real-time detection data from ascanned region of the object to be inspected.

At step 303, working conditions of the radiation emission device'saccelerator are adjusted based on the real-time detection data. In anembodiment, the real-time detection data is a sampling value, at thebeginning of a scanning process (generally, in the event of air or emptyspace), the accelerator has a lower dose rate or a lower output beamenergy level. When the detector detects that the sampling value becomeslarger, it indicates that the object to be inspected entering thedetection range has a smaller mass thickness, thus the output beam doserate or the electron beam output energy level may be decreased. When thesampling value becomes smaller, it indicates that the object to beinspected entering the detection range has a larger mass thickness, thusthe output beam dose rate or the electron beam output energy level maybe increased. In another embodiment, transparency information of theobject to be inspected is used as real-time detection data, when thedetector detects an increase in the transparency information, itindicates that the object to be inspected entering the detection rangehas a smaller mass thickness, thus the output beam dose rate or theelectron beam output energy level may be decreased. When a decrease inthe transparency information is detected, it indicates that the objectto be inspected entering the detection range has a larger massthickness, thus the output beam dose rate or the electron beam outputenergy level may be increased.

In this manner, the accelerator's output beam dose rate and/or electronbeam output energy level may be adjusted in real time during thescanning process, so that detection may be completed in one operationwhile guaranteeing satisfied imaging technical indexes and reducingenvironmental dose level to improve detection efficiency.

FIG. 4 is a flow chart of another embodiment of the scan method of thisinvention.

At step 401, detection is performed with a predetermined standardaccelerator output beam dose rate and an electron beam output energylevel on an object to be inspected in its entirety. Overall scan data ofthe object to be inspected is obtained using a detector.

At step 402, the overall scan data is analyzed to determine a mainscanning region of the object to be inspected. The main scanning regionmay be a low penetration region determined from the overall scan data ora region suspected to be a contraband item.

At step 403, the accelerator output beam dose rate/the electron beamoutput energy level is increased to detect the main scanning regionagain. The particular accelerator output beam dose rate/electron beamoutput energy level may be determined according to the obtained scandata.

In this manner, a main scanning region may be obtained from the scandata, and only the main scanning region is detected using a higheraccelerator output beam dose rate and/or a higher electron beam outputenergy level to realize satisfied imaging technical indexes and areduced environmental dose level. Compared with real-time detection andadjustment, this method has a lower requirement of system response speedand is more accurate, it also allows the object to be inspected to passthrough the detection region at a faster speed.

FIG. 5 is a flow chart of another embodiment of the scan method of thisinvention.

At step 501, a sampling value of an object to be inspected is obtainedusing a detector. In the case of detecting the object to be inspectedwith the same working conditions of the radiation emission device,information of sampling values obtained by the detector is shown in FIG.6. The sampling values detected by the detector change with massthicknesses of the object to be inspected at different locations.

At step 502, the obtained sampling value is compared with apredetermined sampling threshold value. The predetermined samplingthreshold value may comprise a predetermined lower sampling thresholdvalue and a predetermined upper sampling threshold value. If thesampling value is below the predetermined lower sampling thresholdvalue, step 503 is executed; if the sampling value is above thepredetermined upper sampling threshold value, step 504 is executed.

At step 503, because the sampling value is below the predetermined lowersampling threshold value, it is considered that a corresponding locationof the object to be inspected has a larger mass thickness, and theaccelerator output beam dose rate/electron beam energy level will beincreased.

At step 504, because the sampling value is above the predetermined uppersampling threshold value, it is considered that a corresponding locationof the object to be inspected has a smaller mass thickness, and theaccelerator output beam dose rate/electron beam energy level will bedecreased.

In this manner, the obtained sampling value may be compared with thepredetermined threshold value to determine whether it is necessary toadjust the accelerator output beam dose rate/electron beam energy leveland how to adjust the accelerator output beam dose rate/electron beamenergy level, which has advantages of clear in logic, concisecalculation, low requirements of the processing device, and easy to bepopularized and applied. Meanwhile, adjustment is required only if acertain threshold value has been reached, so that the number of timesthe adjustment is performed may be reduced, and the device load may bedecreased.

In an embodiment, several factors must be taken into consideration whendetermining the sampling value, including a current dose rate andangular distribution of the accelerator, the fluctuation in the doserate and various inconsistency between accelerator sparking and theamplification factor of the detector, etc. In an embodiment, divisionmay be performed according to a predetermined detection granularity, andan average value of several selected sampling values obtained by thedetector nearby a main beam may be used as the sampling value, or aminimum value of single-point sampling values within a section may beused as the sampling value of this section. This approximate estimationmethod has a simple operation flow and does not need real-time imagecorrection, so that the processing speed may be increased and systemrequirements may be reduced. In an embodiment, a minimum value may bedetermined through performing filtering on the collected data. Thismethod takes influences on the system and environment into account andmay improve accuracy.

FIG. 7 is a flow chart of another embodiment of the scan method of thisinvention.

At step 701, transparency information of an object to be inspected underradiation scanning is obtained using a detector. If the radiationemission device radiates the object to be inspected under constantworking conditions, transparency information of the object to beinspected in a detection image generated from the data obtained by thedetector is shown in FIG. 8.

At step 702, the obtained transparency information is compared with apredetermined transparency threshold value. The predeterminedtransparency threshold value may comprise a predetermined lowertransparency threshold value and a predetermined upper transparencythreshold value. If the transparency information is below thepredetermined lower transparency threshold value, step 703 is executed;if the transparency information is above the predetermined uppertransparency threshold value, step 704 is executed;

At step 703, because the transparency information is below thepredetermined lower transparency threshold value, it is considered thata corresponding location of the object to be inspected has a larger massthickness, and the accelerator output beam dose rate/electron beamenergy level will be increased.

At step 704, because the transparency information is above thepredetermined upper transparency threshold value, it is considered thata corresponding location of the object to be inspected has a smallermass thickness, and the accelerator output beam dose rate/electron beamenergy level will be decreased.

In this manner, the obtained transparency information may be comparedwith the predetermined threshold value to determine whether it isnecessary to adjust the accelerator output beam dose rate/electron beamenergy level and how to adjust the accelerator output beam doserate/electron beam energy level, which has advantages of clear in logic,concise calculation, low requirements of the processing device, and easyto be popularized and applied. Meanwhile, adjustment is required only ifa certain threshold value has been reached, so that the number of timesthe adjustment is performed may be reduced, and the device load may bedecreased.

In an embodiment, first, initial transparency information of a detectionregion (for example, a column or several columns) may be obtained, asshown by a vertical line in FIG. 8, then initial transparencyinformation is corrected according to a local image and an air image,for example, through subtracting a local image value, dividing by an airimage value or multiplying by a brightness correction coefficient, toobtain transparency information of the object to be inspected. Due todifferences in circuit designs and fabrication processes, differentbackground images may be generated from natural background radiation andcircuit noise data; meanwhile, due to the impact of environment andbrightness, different air images and brightness information may beproduced. In an embodiment, a statistic on transparency information of adetection region (for example, a column or several columns) may beobtained and an average value may be used as the transparencyinformation. In this manner, by means of transparency information of theobject to be inspected which has been corrected based on the impact oftheir environment, device conditions and other factors, detectionaccuracy may be guaranteed.

In an embodiment, ideal accelerator working conditions may be determinedbased on the detection data and a predetermined policy. According to theobtained detection data, based on a predetermined conversion policy,such as a linear relationship or a conversion formula, an idealaccelerator output beam dose rate or an ideal electron beam outputenergy level may be determined, so that working conditions of theradiation emitter may be adjusted based on the ideal values. In thismanner, working conditions of the radiation emitter may be adjusted witha smaller granularity and more accurately, so that detection accuracymay be further improved.

In an embodiment, the accelerator has three output beam dose ratelevels, as shown in FIG. 9, including a high output beam dose rate Ph, astandard output beam dose rate P0 and a low output beam dose rate Pl. Inthe case of detecting the object to be inspected with P0, if thedetection data is above an upper threshold value Th, the output beamdose rate is adjusted to Pl; if the detection data is below a lowerthreshold value Tl, the output beam dose rate is adjusted to Ph. Duringa scanning, working conditions of the radiation emission device may beadjusted several times. In this manner, the accelerator output beam doserate may be adjusted through a simple decision process, and only threeconditions of the output beam dose rate are required for the acceleratorto meet its demands, so that device requirements may be reduced, whichis adverse to popularization and application.

In an embodiment, the accelerator has multiple output beam dose ratelevels, such as P1, P2, . . . Pn(n>3) from low to high, when the objectto be inspected is detected with Px, if the detection data is above anupper threshold value Th, the output beam dose rate is adjusted to Px−1;if the detection data is below a lower threshold value Tl, the outputbeam dose rate is adjusted to Px+1. In this manner, through settingmultiple levels, the output beam dose rate may be controlled moreaccurately and conveniently, and an optimal effect of controllingimaging technical indexes and reducing the environmental dose level maybe achieved.

In an embodiment, three output electron beam energy levels arerepresented by Ph, P0 and Pl as shown in FIG. 9, when the object to beinspected is detected with P0, if the detection data is above an upperthreshold value Th, the output electron beam energy level is adjusted toPl; if the detection data is below a lower threshold value Tl, theoutput electron beam energy level is adjusted to Ph. In this manner, theaccelerator output electron beam energy level may be adjusted through asimple decision process, and only three conditions are required for theoutput electron beam energy level of the accelerator to meet itsdemands, so that device requirements may be reduced, which is adverse topopularization and application.

In an embodiment, the accelerator has multiple output electron beamenergy levels, such as P1, P2, . . . Pn (n>3) from low to high, when theobject to be inspected is detected with Px, if the detection data isabove an upper threshold value Th, the output electron beam energy levelis adjusted to Px−1; if the detection data is below a lower thresholdvalue Tl, the output electron beam energy level is adjusted to Px+1. Inthis manner, through setting multiple levels, the output electron beamenergy level may be controlled more accurately and conveniently, and anoptimal effect of controlling imaging technical indexes and reducing theenvironmental dose level may be achieved.

FIG. 10 shows a schematic view of an embodiment of the radiation scancontroller according to this invention. Wherein, a data acquisitionmodule 1001 is capable of acquiring detection data of an object to beinspected under radiation scanning using a detector. An adjustmentmodule 1002 is capable of adjusting working conditions of a radiationemitter according to the detection data acquired by the detector. Anaccelerator output beam dose rate, or an output electron beam energylevel, or both of them may be adjusted.

This controller may adjust working conditions of the accelerator of theradiation emission device according to the detection data detected bythe detector, so that for a region having a larger mass thickness, ahigher output beam dose rate or a higher electron beam output energylevel is adopted to guarantee satisfied imaging technical indexes, for aregion having a smaller mass thickness, a lower output beam dose rate ora lower electron beam output energy level is adopted to reduce theenvironmental dose level while guaranteeing satisfied imaging technicalindexes.

In an embodiment, the detection data may be a sampling value of thedetector, working conditions of the radiation emitter are adjustedaccording to the sampling value; or the detection data may betransparency information of the object to be inspected obtained by thedetector, and working conditions of the radiation emitter are adjustedaccording to the transparency information. This controller may adjustworking conditions of the radiation emitter according to a samplingvalue obtained by the detector or transparency information of adetection image. This data may be obtained conveniently and may beprocessed conveniently, so that system response speed may be improved.

In an embodiment, the adjustment module may obtain detection data inreal time as the object to be inspected moves relative to the detector,and adjust working conditions for the accelerator of the radiationemission device in real time. In another embodiment, a sampling value isused as the real-time detection data, if the detector detects anincreased sampling value, it indicates that the object to be inspectedentering the detection range has a smaller mass thickness, thus theadjustment module decrease the output beam dose rate or the electronbeam output energy level; if the sampling value becomes larger, itindicates that the object to be inspected entering the detection rangehas a larger mass thickness, the adjustment module increases the outputbeam dose rate or the electron beam output energy level. In anotherembodiment, transparency information of the object to be inspected isused as the real-time detection data, in the case of increasedtransparency information, it indicates that the object to be inspectedentering the detection range has a smaller mass thickness, theadjustment module decreases the output beam dose rate or the electronbeam output energy level; in the case of decreased transparencyinformation, it indicates that the object to be inspected entering thedetection range has a larger mass thickness, the adjustment moduleincreases the output beam dose rate or the electron beam output energylevel.

This controller may adjust the accelerator output beam dose rate and/orelectron beam output energy level in real time during the scanningprocess, so that detection may be completed in one operation whileguaranteeing satisfied imaging technical indexes and reducingenvironmental dose level, so that detection efficiency is improved.

In an embodiment, after a complete scanning, the adjustment moduleanalyzes all scan data to determine a main scanning region of the objectto be inspected, and then detection is performed again for the mainscanning region. The particular accelerator output beam doserate/electron beam output energy level adjusted by the controller may bedetermined according to the obtained scan data.

This controller may obtain a main scanning region from the scan data,and only the main scanning region is detected using a higher acceleratoroutput beam dose rate and/or a higher electron beam output energy levelto realize satisfied imaging technical indexes and a reducedenvironmental dose level. Compared with real-time detection andadjustment, there is a lower requirement of system response speed and itis more accurate. It also allows the object to be inspected to passthrough the detection region at a faster speed.

In an embodiment, as shown in FIG. 11, a data acquisition module 1001 iscapable of acquiring detection data of an object to be inspected underradiation scanning using a detector. An adjustment module 1102 comprisesa comparison unit 1112 and an emission adjustment unit 1122. If thedetection data is a sampling value, the comparison unit 1112 comparesthe sampling value with a predetermined sampling threshold value. If thesampling value is above the predetermined upper sampling thresholdvalue, the emission adjustment unit 1122 decreases the acceleratoroutput beam dose rate and/or the output electron beam energy level; ifthe sampling value is below the predetermined lower sampling thresholdvalue, the emission adjustment unit 1122 increases the acceleratoroutput beam dose rate and/or the output electron beam energy level.

This controller may compare the obtained sampling value with thepredetermined threshold value to determine whether it is necessary toadjust the accelerator output beam dose rate/electron beam energy leveland how to adjust the accelerator output beam dose rate/electron beamenergy level, which has advantages of clear in logic, concisecalculation, low requirements of the processing device, and easy to bepopularized and applied. Meanwhile, adjustment is required only if acertain threshold value has been reached, so that the number of timesthe adjustment is performed may be reduced, and the device load may bedecreased.

In an embodiment, if the detection data is transparency information, thecomparison unit 1112 compares the transparency information with apredetermined transparency threshold value. If the transparencyinformation is above a predetermined upper transparency threshold value,the emission adjustment unit 1122 decreases the accelerator output beamdose rate and/or the output electron beam energy level; if thetransparency information is below a predetermined lower transparencythreshold value, the emission adjustment unit 1122 increases theaccelerator output beam dose rate and/or the output electron beam energylevel.

This controller may compare the obtained transparency information with apredetermined threshold value to determine whether it is necessary toadjust the accelerator output beam dose rate/electron beam energy leveland how to adjust the accelerator output beam dose rate/electron beamenergy level, which has advantages of clear in logic, concisecalculation, low requirements of the processing device, and easy to bepopularized and applied. Meanwhile, adjustment is required only if acertain threshold value has been reached, so that the number of timesthe adjustment is performed may be reduced, and the device load may bedecreased.

In an embodiment, an ideal value determination unit 1112 in FIG. 11 iscapable of determining an ideal accelerator working condition based onthe detection data according to a predetermined policy; based on theobtained detection data, according to a predetermined conversion policy,such as a linear relationship or a conversion formula, an idealaccelerator output beam dose rate or an ideal electron beam outputenergy level may be determined. An emission adjustment unit 1122 adjustsworking conditions of a radiation emitter according to the ideal values.This controller may adjust working conditions of the radiation emitterwith a smaller granularity and more accurately, so that detectionaccuracy may be further improved.

FIG. 12 shows a schematic view of an embodiment of the scan systemaccording to this invention. Wherein, the detector 1201 is capable ofobtaining detection data and sending to a controller. The controller1202 is capable of determining whether it is necessary to adjust theaccelerator output beam dose rate/electron beam energy level and how toadjust the accelerator output beam dose rate/electron beam energy level,generating control information and sending to the radiation emitter. Theradiation emitter 1203 is capable of radiating on object to be inspectedand adjusting working conditions of an accelerator according to thecontrol information obtained from the controller 1202.

This scan system may adjust working conditions of the accelerator of theradiation emission device according to the detection data detected bythe detector, so that for a region having a larger mass thickness, ahigher output beam dose rate or a higher electron beam output energylevel is adopted to guarantee satisfied imaging technical indexes, for aregion having a smaller mass thickness, a lower output beam dose rate ora lower electron beam output energy level is adopted to reduce theenvironmental dose level while guaranteeing satisfied imaging technicalindexes.

In an embodiment, as shown in FIG. 13, a radiation emitter emits X-rayto an object to be inspected, the X-ray penetrates the object to beinspected and reaches a detector. The detector acquires detection dataand forwards to a controller. The controller determines whether to andhow to adjust working conditions of the radiation emitter based on thedetection data. If it is required to adjust working conditions of theradiation emitter, control information is generated and sent to theradiation emitter for adjustment, to control the accelerator of theradiation emitter to increase or decrease its output beam doserate/output electron beam energy level.

Through coordination between the radiation emitter, the detector and thecontroller, working conditions of the radiation emitter are adjustedaccording to the mass thickness of the object to be inspected andparticular situations, so that satisfied imaging technical indexes maybe guaranteed while reducing the environmental dose level.

It shall be noted that: the above embodiments are merely illustration ofthe technical solution of this invention, but are not limitationthereof. Although this invention has been described in detail withpreferred embodiments, those ordinary skilled in the art shallunderstand: embodiments of the present invention may be modified or sometechnical features thereof may be substituted equivalently, withoutdeparting from the spirit of the technical solution of this invention,all of which shall be encompassed in the scope of the technical solutionas claimed in this invention.

What is claimed is:
 1. A scan method, comprising: acquiring detectiondata of an object to be inspected under radiation scanning using adetector, comprising: dividing data acquired by the detector intosections according to a predetermined detection granularity; using anaverage value of the data acquired by the detector from the same sectionas a sampling value, or extract a minimum value of the data acquired bythe detector from the same section as a sampling value; and using thesampling value as the detection data; adjusting an accelerator outputbeam dose rate and/or an output electron beam energy level of aradiation emission device according to the detection data, comprising:comparing the sampling value with a predetermined sampling thresholdvalue; if the sampling value is below a predetermined lower samplingthreshold value, increasing the accelerator output beam dose rate and/orthe output electron beam energy level; if the sampling value is above apredetermined upper sampling threshold value, decreasing the acceleratoroutput beam dose rate and/or the output electron beam energy level. 2.The method according to claim 1, wherein adjusting an accelerator outputbeam dose rate and/or an output electron beam energy level of aradiation emission device according to the detection data comprises:during a movement of the object to be inspected relative to theradiation emission device and the detector, adjusting an acceleratoroutput beam dose rate and/or an output electron beam energy level of aradiation emission device according to real-time detection data obtainedby the detector from a scanning region of the object to be inspected. 3.The method according to claim 1, wherein adjusting an accelerator outputbeam dose rate and/or an output electron beam energy level of aradiation emission device according to the detection data comprises:acquiring overall scanning data of the object to be inspected using thedetector; analyzing the overall scanning data to determine a mainscanning region of the object to be inspected, wherein the main scanningregion comprises a low penetration region or a region suspected to be acontraband item; determine an accelerator output beam dose rate and/oran output electron beam energy level according to detection data of themain scanning region, to scan the main scanning region.
 4. The methodaccording to claim 1, wherein adjusting an accelerator output beam doserate and/or an output electron beam energy level of a radiation emissiondevice according to the detection data comprises: determining an idealoutput beam dose rate and/or an ideal output electron beam energy levelaccording to a conversion policy for converting the detection data tothe ideal accelerator output beam dose rate and/or the ideal outputelectron beam energy level; adjusting the accelerator output beam doserate and/or the output electron beam energy level to the ideal outputbeam dose rate and/or the ideal output electron beam energy level. 5.The method according to claim 1, wherein the accelerator of theradiation emission device comprises multiple output beam dose ratelevels and/or multiple output electron beam energy levels, each levelhaving a fixed output beam dose rate and/or a fixed output electron beamenergy value; adjusting an accelerator output beam dose rate and/or anoutput electron beam energy level of a radiation emission deviceaccording to the detection data comprises: adjusting the acceleratoroutput beam dose rate and/or the output electron beam energy level ofthe radiation emission device to a certain level according to thedetection data.
 6. A radiation scan controller, characterized incomprising: a data acquisition module for acquiring detection data of anobject to be inspected under radiation scanning using a detector,comprising: dividing data acquired by the detector into sectionsaccording to a predetermined detection granularity; using an averagevalue of the data acquired by the detector from the same section as asampling value, or extract a minimum value of the data acquired by thedetector from the same section as a sampling value; and, using thesampling value as the detection data; an adjustment module for adjustingan accelerator output beam dose rate and/or an output electron beamenergy level of a radiation emission device according to the detectiondata, wherein the adjustment module comprises: a comparison unit forcomparing the sampling value with a predetermined sampling thresholdvalue; an emission adjustment unit for, if the sampling value is below apredetermined lower sampling threshold value, increasing the acceleratoroutput beam dose rate and/or the output electron beam energy level; ifthe sampling value is above a predetermined upper sampling thresholdvalue, decreasing the accelerator output beam dose rate and/or theoutput electron beam energy level.
 7. The controller according to claim6, wherein the adjustment module is further used for: during a movementof the object to be inspected relative to the radiation emission deviceand the detector, adjusting an accelerator output beam dose rate and/oran output electron beam energy level of a radiation emission deviceaccording to real-time detection data obtained by the detector from ascanning region of the object to be inspected.
 8. The controlleraccording to claim 6, wherein the adjustment module is further used for:acquire overall scanning data of the object to be inspected; analyzingthe overall scanning data to determine a main scanning region of theobject to be inspected, wherein the main scanning region comprises a lowpenetration region or a region suspected to be a contraband item;determine an accelerator output beam dose rate and/or an output electronbeam energy level according to detection data of the main scanningregion, to scan the main scanning region.
 9. The controller according toclaim 6, wherein the adjustment module further comprises: an ideal valuedetermination unit for determining an ideal output beam dose rate and/oran ideal output electron beam energy level according to a conversionpolicy for converting the detection data to the ideal accelerator outputbeam dose rate and/or the ideal output electron beam energy level; anemission adjustment unit for adjusting the accelerator output beam doserate and/or the output electron beam energy level to the ideal outputbeam dose rate and/or the ideal output electron beam energy level. 10.The controller according to claim 6, wherein the accelerator of theradiation emission device comprises multiple output beam dose ratelevels and/or multiple output electron beam energy levels, each levelhaving a fixed output beam dose rate and/or a fixed output electron beamenergy value; the adjustment module is further used to adjust theaccelerator output beam dose rate and/or the output electron beam energylevel of the radiation emission device to a certain level according tothe detection data.
 11. A scan system, comprising: a radiation scancontroller, comprising: a data acquisition module for acquiringdetection data of an object to be inspected under radiation scanningusing a detector, comprising: dividing data acquired by the detectorinto sections according to a predetermined detection granularity; usingan average value of the data acquired by the detector from the samesection as a sampling value, or extract a minimum value of the dataacquired by the detector from the same section as a sampling value; and,using the sampling value as the detection data; a detector; and aradiation emitter; wherein the detector is used to send detection datato the radiation scan controller; the radiation scan controller is usedto send control information to the radiation emitter for adjusting anaccelerator output beam dose rate and/or an output electron beam energylevel of the radiation emission device according to the detection data;the radiation emitter is used for emitting radiation; and adjusting anaccelerator output beam dose rate and/or an output electron beam energylevel of a radiation emission device according to the detection data,comprising: comparing the sampling value with a predetermined samplingthreshold value; if the sampling value is below a predetermined lowersampling threshold value, increasing the accelerator output beam doserate and/or the output electron beam energy level; if the sampling valueis above a predetermined upper sampling threshold value, decreasing theaccelerator output beam dose rate and/or the output electron beam energylevel.